A machinist's square or engineer's square is the metalworkers' equivalent of a try square. It consists of a steel blade inserted and either welded or pinned into a heavier body at an angle of 90°. Thus, the blade and the body typically define an angle that is very nearly a right angle, within the manufacturing tolerances of the square. A machinist's square is typically purchased as one of a set of squares of different sizes to accommodate different sizes of workpieces.
In use, the body of the square is aligned against one edge of the object and the blade is presented to the end or body of the object to be measured. If the end is being checked, then a strong light source behind the square will show any mismatch between the blade of the square and the end of the object. The mismatch will appear as a thin, acute triangular sliver of light between the square and the object being measured. The purpose of this action is to either check for squareness or to mark out the body of the workpiece.
One can immediately appreciate that this measurement technique is dependent on the skill of the machinist and, even among the most skillful machinists in the art, introduces a certain subjectivity to the measurement. If the square is placed at an inappropriate angle to the body, then the body may appear to be square while having an unacceptable error. Even if the square is properly placed against the workpiece and an error in the angle of measurement is indicated, the machinist can only estimate that amount of the error. Thus, there remains a need for a tool which is automatically adjustable to conform to the angle under measurement and provide an indication and an objective measure of the degree of error in the measurement. The present invention is directed to filling this need in the art.